With the development of the communication system, the OTN becomes the mainstream of the transmission network gradually, and in particular, the development of the cross switch technology based on the OTN makes the OTN develop into a bearing platform of the multiple services gradually. However, in some services or application systems, it is required to transparently transfer the client signal clock.
The traditional solution is to adopt the synchronous mapping way, that is, the service clock is used to perform encapsulating to the service data flow in OTN. This kind of application requires that there is a fixed frequency ratio between the accessing service and the OTN service, and the transparent transferring of the multi-channel customer service clock cannot be realized, which has more restrictions in the applications.
The asynchronous mapping way is mostly adopted when the customer service is transmitted through the OTN, that is, the service data flow is read in the service accessing end according to the service clock, and then the read service data flow is encapsulated into an OTN payload according to the OTN clock. After adopting this mapping way, the service clock information will be kept in the service data flow, so the service clock information needs to be recovered at the OTN receiving end.